ticket cut-off dates for recurring events

<?php
/*
This snippet will make tickets named 'Early Bird' unavailalble 10 days before an event.
Could be useful for creating recurring events, as cut-off dates won't work in these cases.
*/
function my_em_ticket_is_available($result, $EM_Ticket){

    $date_today = date('Y-m-d');
    $event_start_date = $EM_Ticket->get_event()->event_start_date;
    $nodays = date_diff($date_today,$event_start_date);

    if ( $EM_Ticket->ticket_name == 'Early Bird' && $nodays < 10 ) {
        return false;
    }

    return $result;
}
add_filter('em_ticket_is_available','my_em_ticket_is_available',10,2);

function date_diff($date1, $date2) {
    $current = $date1;
    $datetime2 = date_create($date2);
    $count = 0;
    while(date_create($current) < $datetime2){
        $current = gmdate("Y-m-d", strtotime("+1 day", strtotime($current)));
        $count++;
    }
    return $count;
}
?>